Issue: the info in fail is always non-nullptr
issue: no checking to memory allocation of rmw_client, which
       may leads to free nullptr in the following code:

  rmw_client_free(rmw_client);

Issue: uninteded memory free from rmw_client->service_name:

  if (rmw_client->service_name != nullptr) {
    rmw_free(const_cast<char *>(rmw_client->service_name));
    rmw_client->service_name = nullptr;
  }

when the code goes to fail before it's actually allocated here:

  rmw_client->service_name = reinterpret_cast<const char *>(
    rmw_allocate(strlen(service_name) + 1));

Signed-off-by: Ethan Gao <[email protected]>

into fail even though it's no possible to trigger it now

Signed-off-by: Ethan Gao <[email protected]>